- Changes user's type to type of last attack that hit this Pokémon.
Level 100 Statistics (see level 5, 50, 100)
Kecleon is cool and actually somewhat usable in OU play, with easy switch-ins on a lot of special Pokemon and the ability to screw your opponent up with moves like Trick. In UU, it can wall a ton of special hits and can attack moderately hard with its base 90 Attack.
Kecleon has a decent Attack stat in UU matches, and STAB on Return lets it really hit some Pokemon hard. When Kecleon reaches the end of its run, you can always Trick some unsuspecting Pokemon and really hurt it for the rest of the match.
Kecleon has a high Special Defense stat and can use this to wall many special attackers such as Electabuzz (without Cross Chop, which few have in UU). Double-Edge is an option because you are using Rest to constantly restore Kecleon's HP, but with only 324 max HP, recoil still hurts. The last slot is mostly for Rock-type Pokemon. Brick Break hits Aggron on its 4x weakness, rather than neutral, while the Steel moves hit Solrock and Lunatone as well as any Misdreavus and Sableye you may encounter. Iron Tail vs. Hidden Power Steel is really just a question of power vs. accuracy.
Skill Swap is a nice twist; you'll probably want to use it with Shadow Ball. Kecleon doesn't really work as a special attacker overall, but you could probably nail Gyarados and Salamence. Magic Coat is a really cool move, but it's usually more reliable to just use Thunder Wave. Toxic can force things like Suicune to Rest, while Psych Up can steal Calm Minds. Kecleon can use Substitute + Focus Punch, as it has the horrible Speed to do it.
Always max Kecleon's dismal HP; it will really help it take special hits. You generally don't want to bother with Defense, so just focus on Attack and Special Defense. If you are using Substitute + Focus Punch, give Kecleon a -Speed nature to ensure it goes last on the turn it Substitutes, so it can Focus Punch next turn uninterrupted.
Checks and Counters
Blissey, Suicune, etc. Anything that can take advantage of its ability, has high Attack, or has high HP. Most counters can be messed up with Trick though, which just makes Kecleon even cooler.